Bureau International des Poids et Mesures

GUM’s contribution to the International Metrology in Chemistry Programme at the BIPM

R. I. Wielgosz (BIPM)

Bureau International des Poids et Mesures

1Bureau International des Poids et Mesures

Bureau International des Poids et Mesures

OUTLINE OF PRESENTATION

• BIPM, International Metrology, National Metrology Institutes

• Visiting Scientist secondment programme to the BIPM

• Standards and comparisons for Atmospheric Composition: Air Quality and Greenhouse Gases

• Conclusions and future outlook

Bureau International des Poids et Mesures

BUREAU INTERNATIONAL DES POIDS ET MESURES

The BIPM is an intergovernmental organization established by the Metre Convention, through which Member States act together on matters related to measurement science and measurement standards.

www.bipm.org

The mission of the BIPM is to ensure and promote the global comparability of measurements, including providing a coherent international system of units for:• Scientific discovery and innovation,• Industrial manufacturing and international trade,• Sustaining the quality of life and the global environment.

BIPM Chemistry Department includes programme on:

International equivalence of gas standards for air quality and climate change monitoring

Coordinating comparisons of gas standards with the National Metrology Institutes and Designated Institutes within the CCQM Gas Analysis Working Group

Bureau International des Poids et Mesures

Visiting Scientists to the BIPM Chemistry Department

J. Norris (NIST) 16 June – 1 Aug 2003M. Sega (INRIM) 5 Sept – 2 Dec 2005T. Ihara (NMIJ) 10 Oct – 10 Nov 2005A. Rakowska (GUM) 31 Jan – 27 Apr 2006Y. Shimitzu (NMIJ) 21 Aug – 15 Sept 2006J. Guardado (CENAM) 30 March – 31 July 2007C. Dazhou (NIM) 27 Aug- 20 Nov 2008G. Ochmann (GUM) 1 Sept – 30 Nov 2008C. Dazhou (NIM) 1 Oct – 4 Dec 2009P. Mitchell (NMIA) 1 July - 30 Sept 2011K. Tworek (GUM) 1 June – 30 Nov 2012S. Lee (KRISS) 1 March – 31 May 2013M. Lee (NIM) 1 May 2013 – 30 November 2015C. Pascal (METAS) 1 March 2014 – 30 July 2015D. Song (NIM) 1 June 2014 – 30 Nov 2014M. Minarro (NPL) 1 Sept 2014 – 30 Nov 2014B. Garrido (INMETRO) 1 Feb 2015 – 31 May 2015

Greenhouse and Air Quality Gases

GASRecent

tropospheric concentration

Carbon dioxide (CO2) 392.6 µmol/molMethane (CH4) 1874 nmol/molNitrous oxide (N2O) 324 nmol/molTropospheric ozone (O3) 34 nmol/mol

Halocarbons (0.003 to 0.5) nmol/mol

Pollutant Concentration Averaging period

Ozone 60 nmol/mol Maximum daily 8 hour mean

Sulphur dioxide (SO2) 120 nmol/mol 1 hour 45 nmol/mol 24 hours

Nitrogen dioxide (NO2) 100 nmol/mol 1 hour 20 nmol/mol 1 year

Carbon monoxide (CO) 8 µmol/mol Maximum daily 8 hour mean

Benzene 1.5 nmol/mol 1 year Fine particles (PM2.5) 25 µg/m3 1 year PM10 50 µg/m3 24 hours

40 µg/m3 1 year Lead (Pb) 0.5 µg/m3 1 year

Air Quality

Greenhouse Gases

2010 WMO-BIPM workshop on “

Measurements Challenges for Global Observation Systems for Climate Change Monitoring

’’Signature of CIPM-MRA by WMO

WMO-BIPM Workshop

http://www.bipm.org/en/events/wmo-bipm_workshop/6Bureau International des Poids et Mesures

Wielgosz R., Calpini B., (Editors), Report on the WMO-BIPM workshop on Measurement Challenges for Global Observation Systems for Climate Change Monitoring: Traceability, Stability and Uncertainty, Rapport BIPM-2010/08, 100 pp

Ozone StandardReferencePhotometer

BAKI titration

Gas Phasetitration

GravimetryNO / NO2

Gas standards

Absorptioncross section

(UV)

Absorptioncross section

(IR)

Opticalmeasurements

of pure O3

PressureVolume

Temperature

GravimetryIodide

standards

Atmospheric Ozone Measurements

(Total Column, Stratospheric) (Surface ozone)

Dobson and BrewerSpectrophotometers

Satellite basedmeasurement

systems

FTIR basedsystems

UV ozonephotometers

Establishing Traceability for Atmospheric Ozone Measurements

BIPM-NIST programme to maintain the comparability of the worldwide network of ozone reference standards

Surface Ozone Standards and Comparisons

NIS

T

ISC

III

ERLA

P

Envi

ronm

ent C

anad

a

MET

AS

SRP1

8

MET

AS

SRP1

4

KR

ISS

LNE

VNIIM FM

I

WM

O/W

CC

-EM

PA

UB

A (A

)

SP

NPL

ND

ENW

UB

A (D

)

NIE

S

CH

MI

CSI

R-N

ML(

1)

NER

I

NIL

U

NM

i-VSL

IMG

C

CSI

R-N

ML

(2)

BIP

M G

PT

NIE

S G

PT

-20

-15

-10

-5

0

5

10

15

20

Deg

ree

of e

quiv

alen

ce (nm

ol/m

ol)

(k=2)

GPT

UV Photometric Methods

2.5% bias relative to UV

method

CCQM-P28 Degrees of Equivalence, Ozone mole fraction:420 nmol/mol

Progress Report (2004-2005)

NO2 primary facility (dynamic preparation)

Ozone reference standard

comparison facility

CCQM-P28BIPM.QM-K1

Ozone (2-1000) nmol/mol

CCQM-P73NO (30-70) µmol/mol

Gas Phase TitrationNO + O3 NO2 + O2

CCQM-K74 (including validation of

spectroscopic methods)

-7.000

-6.000

-5.000

-4.000

-3.000

-2.000

-1.000

0.000

1.000

2.000

3.000

KR

ISS

(M1)

KR

ISS

(M15

)C

SIR

-NM

L (M

2)C

SIR

-NM

L (M

16)

CE

RI (

M3)

CE

RI (

M14

)V

ALC

RM

1 (M

4)V

ALC

RM

2 (M

11)

VA

LCR

M3

(M17

)LN

E (M

5)LN

E (M

19)

SM

U (M

6)S

MU

(M18

)C

EN

AM

(M7)

CE

NA

M (M

20)

VN

IIM (M

8)V

NIIM

(M22

)N

IST

(M9)

NIS

T (M

24)

NM

IA (M

10)

NM

IA (M

23)

IPQ

(M12

)IP

Q (M

25)

NM

i-VS

L (M

13)

NM

i-VS

L (M

21)

 NP

L  N

IST 

 NM

i-VS

L  B

NM

-LN

E 

 KR

ISS

  N

RLM

*  N

RC

CR

M 

 VN

IIM 

 OM

H 

 BN

M-L

NE

  N

PL 

 VN

IIM 

 NM

i-VS

L  G

UM

  C

EM

  M

ETA

S 

 CH

MI 

 FM

I  IP

Q 

Laboratory (cylinder)

D/ m m

ol/m

ol

CCQM-P73 (LIMAS 11UV analysis) CCQM-K1.c EUROMET-K1.c

4000 3500 3000 2500 2000 1500 1000

0.00

0.05

0.10

0.15

0.20

Abs

orba

nce

Wavenumber / cm -1

GPT Experiment Sequence

0

200

400

600

800

1000

1200

0 50 100 150 200 250 300 350 400

time / minutes

[NO

], [O

3] /

(nm

ol/m

ol)

cycle 1 cycle 2 cycle 3 cycle 4 cycle 5

Nitrogen Monoxide Comparison

NO2

Differences in Reference Methods for Ozone

Consider ozone partial pressure, as decomposition 2O3 -> 3O2 will rapidly occur

3ln( )

2( )Oopt i T

T RL P P Na

Measure O2 and other impurities, as O3 will never be “pure” (max ~99%)

Lopt to be measured by interferometry

Ozone cross-section a measurement challenge

Ozone generator (high voltage discharges)

5 cm absorption cell

Large range pressure gauge

High accuracy pressure gauge (Baratron) for P < 1 mbar

Mass spectrometer

Temperature controlled cryostat

Frequency doubled argon-ion laser with intensity stabilisation

BIPM facility for ozone cross section measurements

• Double walls tube in glass

• Inside/outside electrodes to apply high voltage

• Discharges in oxygen produce ozone

20 kV, 50 kHz

• Entire system inside temperature controlled cryostat

• Ozone trapped in liquid form

• Pumping to remove remaining oxygen

• Slow temperature increase release pure gas-phase

ozone

Liquid ozone trapped at 80 K

Cryogenic Ozone Generator

Michelson interferometer to deduce Lopt in the cell in which the pressure is varied

a01

2n L F

n : index of refraction of air L0 / m : light path length F : number of fringesa / m : laser wavelength

8 2 1 2 1 810 8342.54 2406147(130 ) 15998(38.9 ) 1 10 0.601 0.009721

96095.43 1 0.003661

p T pn

T

Pressure in the cell: 1 bar -> 0.1 mbar -> F fringes on the photodiode -> Path length L0

Edlen formula for the air index of refraction at pressure P and temperature T

Absorption pathlength measurements by interferometry

Typical valuesStarting pressure Pi = 1012 hPa Temperature T = 22.39°CLaser l = 632.991 nm F = 42.37 fringes

Giving Lopt = 4.978 cm, u(Lopt) = 0.012 cm

Fringes signal on photodiode recorded with Labview:

Fringes are counted with Labview as well => most important uncertainty component

Last series of measurements

0 2 4 6 8 104.95

4.96

4.97

4.98

4.99

5.00

5.01

path

leng

th (c

m)

Measurement number

Lopt = 4.978 cm with u(Lopt) = 0.012 cm

Absorption pathlength measurements by interferometry

Absolute measurements of ozone cross-section with the UV-laser

245 250 255 260-1.0

-0.5

0.0

0.5

1.0 This work Gorshelev BDM Burrows

(

bogu

mil) /

10-1

8 cm

2 mol

ecul

e-1

/ nm

Accurate laser measurements of ozone absorption cross-sections in the Hartley band

0.2 0.4 0.6 0.8 1.00.985

0.990

0.995

1.000

x(O

3) / (m

ol m

ol-1)

P (sample) / (mbar) Liquid ozone trapped at 80 K

Cryogenic ozone generator Evaporation-condensation cycles Impurity analysis by RGA & FTIR

Ozone purity better than 99%

BIPM values in agreement with absolute measurements (in pure ozone)

Lowest uncertainty : 0.6%

Accurate laser measurements of ozone absorption cross-sections in the Hartley band.J. Viallon , S. Lee , P. Moussay, K. Tworek , M. Petersen , R.I.WielgoszSubmitted to Atmospheric Measurement Techniques

Bureau International des Poids et Mesures

NO2 standards and comparison (10ppm)CCQM GAWG key comparison on NO2 and Spectroscopic Measurements

The Air Quality Strategy for England, Scotland, Wales and Northern Ireland

Objectives (for 2020) for particulate matter (PM10), nitrogen dioxide (NO2), ozone (O3), and polycyclic aromatic hydrocarbons (PAHs) are unlikely to be achieved, without further measures

BIPM dynamic gas standard facility for NO2

Flow Control System for Rubotherm1. Zero air generator2. Nitrogen Generator3. Nitrogen Cylinders4. molbloc (0-1000) mL/min5. SAES Nitrogen purifier6. Mass flow controller (0-100) mL/min7. Mass flow controller (0-1000) mL/min

Rubotherm System (dynamic gas mixtures)8. Magnetic suspension balance9. NO2 permeation tube

Flow Control System for NO2 Gas Standards10.Mass flow controller (0-1000) mL/min11.Multi position valve (16-ports)

11

waste

waste

10

V

8Flow Control System for Rubotherm

Flow Control System for NO2 Gas Standards

V

P

1

V3

3

2

Rubotherm System

P

P

7

6

4

5

P

P

9

BIPM facility for NO2 Standards

Bureau International des Poids et Mesures

2000 1800 1600 1400 1200 1000

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

H2O

HNO3

NO2 HNO

3

Abs

orba

nce

/Abs

Wavenumber /cm-1

N2O

4

H2O

Infrared absorbance spectrum of a 150 μmol mol−1 NO2/N2 gas mixture generated using the small NO2 permeation device

Quantification of HNO3 without gas standards?

N2O4 negligible impurity at lower concentrations

Purity and quantification of permeating gas: Analysis by FTIR

20Bureau International des Poids et Mesures

xNO2 - NO2 mole fraction;

P - NO2 permeation rate;

Vm - molar volume of nitrogen;

MNO2 - the molar mass of NO2;

qv - total flow of nitrogen;

MHNO3 - the molar mass of NO3; and

xHNO3 - HNO3 mole fraction measured by FTIR.

2

33

2

2NO

HNOHNO

NO

mNO M

xMMqVPx

v

17.82

17.83

17.84

17.85

17.86

17.87

17.88

17.89

17.9

04/12/200712:00:00

05/12/200700:00:00

05/12/200712:00:00

06/12/200700:00:00

06/12/200712:00:00

07/12/200700:00:00

07/12/200712:00:00

08/12/200700:00:00

08/12/200712:00:00

09/12/200700:00:00

NO2 Permeation Rate and Impurities

• Resolution: 2 μg;• Stability,3 days: ~ 0.5 μg;

NO2 permeation rate, P, (5000-10000) ng/min u 2 ng/min

FTIR gas facility

Flores E., Idrees F., Moussay P., Viallon J., Wielgosz R., Highly Accurate Nitrogen Dioxide (NO2) in Nitrogen Standards Based on Permeation, Anal. Chem., 2012, 84(23), 10283-10290

HNO3 quantification using MALT

21Bureau International des Poids et Mesures

HNO3

H2O

NO2

0.050

0.080

0.110

0.140

0.170

0.200

0.230

8.0 9.0 10.0 11.0 12.0 13.0BIPM_NO2 Facility XNO2 μmol/mol

MA

LT c

alcu

latio

n of

HN

O3

μm

ol/m

ol

6.45 m 48.12 m

Uncertainty budget for the HNO3 for mole fractions of (0.1-0.2) µmol/mol

2HNO2

HNO2

HNO 33305.0017.0020.0)( xxxu

Signal stability MALT-CLS HITRAN database

Quantity Typical value Standard uncertaintyRelative

uncertainty

P 8.3573 μg min−1 4.18×10−3 μg min−1 5×10-4

Vm 22.4038 L mol−1 0.34×10-3 L mol−1 1.52×10-5

qv 452 mL min−1 0.455 mL min−1 1.00×10-3

MNO2 46.0055 g mol−1 1.40×10−3 g mol−1 3.04×10-5

xHNO3 0.104 μmol mol−1 0.021 μmol mol−1 2.02×10-1

MHNO3 63.013 g mol−1 1.17×10−3 g mol−1 1.86×10-5

xN2O4 0 nmol mol−1 0.866 nmol mol−1 N.A.

Quantity Value Standard Uncertainty

xNO2 8.86 μmol mol-1 0.03 μmol mol−1

Uncertainty budget for NO2 standards

2

33

2

2NO

HNOHNO

NO

mNO M

xMMqVPx

v

Accurate FT-IR spectroscopy measurements of nitrogen dioxide (NO2) and nitric acid (HNO3) calibrated with synthetic spectra, Edgar Flores*, Joële Viallon, Philippe Moussay and Robert Ian Wielgosz (APPLIED SPECTROSCOPY 67 (10), 1171-1178, 2013)

22Bureau International des Poids et Mesures

Bureau International des Poids et Mesures 23Bureau International des Poids et Mesures

Value assignment of cylinders with BIPM NO2 facility (KCRV)Flores E., et al. Final report on international comparison CCQM-K74: Nitrogen dioxide, 10 µmol/mol, Metrologia, 2012, 49, Tech. Suppl., 08005

Results of international comparison for NO2 standards (CCQM-K74)

Transfer Gas Standard NO2 mixture developed by VSLAmount of substance fraction~10 μmol/mol

Passivated aluminum cylinders of 5 L.

Bureau International des Poids et Mesures 24Bureau International des Poids et Mesures

Conclusions and Acknowledgments

• Strong collaboration and support of GUM through visiting scientists highly valued

• Leads to innovation and improved international agreement of standards at low levels of uncertainty

• Important for monitoring and decision making on Air Quality and Greenhouse Gas Measurements

• Many thanks to GUM and Krzysztof Tworek, Grzegorz Ochmann and Agata Rakowska

Future Outlook• BIPM welcomes the support of GUM for its continued programme into

2016-2019, addressing:• Carbon dioxide and Methane Standards (CCQM-K120)• Formaldehyde Standards (CCQM-K90)• Nitrogen Monoxide Standards